The present invention relates to a system terminal for a local loop and more particularly to a system terminal for a local loop connected to a plurality of telephones and connected to a base station for the loop by a radio channel.
One of conventional system terminals for a wireless local loop includes a radio section, a PHS protocol decoding/encoding and, speech generation/speech bus control section, a CPU (Central Processing Unit), and an SLIC (Subscriber Line Interface Circuit). A plurality of telephones each are connected to the system terminal by a respective connection line. The system terminal having the SLIC shared by a:plurality of telephones is lower in cost than a system terminal having a plurality of SLICs each being assigned to a particular telephone.
However, a deficiency of the above conventional system terminal is that it cannot control the telephones individually or allow them to communicate with each other.
Technologies relating to the present invention are disclosed in, e.g., Japanese Patent Laid-Open Publication Nos. 9-322254 and 9-326869 and Japanese Published PCT Application Nos. 9-507625 and 9-510337.
It is therefore an object of the present invention to provide a system terminal for a wireless local loop capable of controlling telephones connected thereto individually with a simple construction.
A system terminal for a wireless local loop connected to a plurality of telephones and connected to a base station for the loop by a radio channel of the present invention includes an open circuit detection circuit for detecting an open circuit state and an on-hook/off-hook state between the system terminal and the individual telephone, and storing the results of detection. A radio section is connected to the radio channel. An encoder/decoder selectively encodes a speech channel to be input to the radio section or decodes a speech signal received via the radio section. A single interface interfaces the plurality of telephones and the encoder/decoder. A two-wire selector connects one of the plurality of telephones to the single interface at a time. A CPU controls the two-wire selector. An interrupt controller interrupts the CPU in accordance with states detected by the open circuit detection circuit.